Question

Feedback inhibition of enzymes is affected by which of the following?
A. Enzyme
B. Substrate
C. End products
D. Intermediate end products

Answer 1

Hint: Feedback inhibition is very essential for a metabolic pathway such as glycolysis to function properly. The product in a reaction that is involved in the feedback inhibition process exhibits both positive and negative inhibition. Positive inhibition involves further production of the output, whereas, negative inhibition stops the production of further output in a set of reactions.

Complete step by step answer: Feedback inhibition is a mechanism in which an enzyme’s activity is inhibited by the enzyme’s end product. It takes place in an allosteric enzyme that possesses both allosteric and active sites. Feedback inhibition usually occurs when the accumulation of a product is more than the optimal amount. Substances which bring about reversible changes are called modulators/site effector/allosteric substances. Allosteric modulators are of two types for activation and inhibition.
The inhibition is reversible. Inhibitors are generally product of reactions, also called the end product inhibition or feedback inhibition. The classical example of feedback inhibition is inhibition of the enzyme hexokinase by glucose-6-phosphate. Feedback inhibition has a regulatory role in preventing the excess formation of the product. It is used in the study of metabolic pathways. It can show the mechanism of enzyme action.
So, the correct answer is option C. End products.

Note: When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as a competitive inhibitor. Due to close structural similarity with the substrate the inhibitor competes with the substrate for substrate binding site of the enzyme.
 Sulpha drugs having sulphanilamide inhibits the synthesis of folic acid in bacteria by competing with para-aminobenzoic acid(PABA). This inhibition gives evidence for lock and key hypothesis of enzyme action.